A heat exchanger for various kinds of liquid and gaseous fluids includes a tubular conduit having a corrugated heat exchanging outer wall and a stationary baffle and turbulator plate mounted inside each corrugation. The turbulator plates divert the fluid flow radially into contact with the large surface areas of the corrugations and a ribbed construction on each turbulator plate adds to the turbulence of the fluid flow to enhance heat exchange. As assembly of tubular conduits is provided with quick disconnect attachments whereby individual conduits may be easily removed and replaced.